The mailbox door is an item found in Freddi Fish 4: The Case of the Hogfish Rustlers of Briny Gulch. When Freddi and Luther encounter E. Tippet who is waiting for a package, they found that his mailbox door is lose and doesn't have a handle. When they fix U's mailcart, Luther accidently says the word glue, which cause Elmer to become spooked. Elmer gallops across the sea bed and crashes in E. Tippet's house. But despite getting trampled, he was happy that his package was delivered at last, which turned out to be a new and improved mailbox door with a handle on it. Freddi and Luther takes his old mailbox door and uses it as part of the belt buckle they need to rescue the hogfish.